Radar Homing Guidance for Tactical Missiles

The frequent minor wars of the last two decades have brought to the fore the guided missile as a weapon against all types of military target. Notable are the successful use of surface to air missiles in the Israeli-Arab war of 1973, the sink- ing of the destroyer Eilat by a Russian-made anti-ship missile, and the extensive use of surface to air and air to air missiles in the Vietnam conflict; more recent are the extensive and devastating use of surface to air, air to air, and anti-ship missiles in the Falkland Islands war of 1982 and the successful use of surface to air missiles in the hands of small irregular forces.
In a free-flight weapons system, such as an artillery shell fired from a gun, the location and any movement of the target are measured as accurately as possible up to the moment of firing and a point of impact is calculated, based upon prediction of the movement of the target during the time of flight of the projec- tile. Two sources of major error exist in this process: firstly the target may change course or speed during the time of flight, and secondly the projectile may not follow the expected trajectory because of errors in the velocity and direction of projection and of unpredictable variations in the meteorological conditions prevailing over the flight path. A guided weapon system avoids both these sources of error by monitoring continuously the flight of the missile with respect to the position and movement of the target, thereby ensuring a much higher probability of a kill. The probability of destroying an airborne target by sustained gunfire is about 10 per cent at best; with a guided missile it can be as high as 50 per cent with a single shot.